1. Field of the Invention
This invention relates to railroad car couplers and particularly to couplers used on railroad freight cars that remain coupled while the car is rotated or inverted to an upside down position to dump the car contents.
2. Prior Art
To facilitate rapid sequential emptying of hopper and gondola type railroad freight cars carrying such bulk commodities as coal, each car is provided with a front rotary type coupler, for example. The front rotary coupler is mated to a rear fixed type coupler of a car forward thereto while a rear fixed coupler is mated to a front rotary type coupler of a car to the rear thereof.
Upon a particular car entering a dump or unload station, the car is rotated toward an upside down position to produce a gravity release of its contents. During this movement, the car rotates about its front rotary coupler while the opposite or rear fixed coupler rotates with the car.
Under these operating conditions, Association of American Railroad (AAR) Type E or Type F couplers should not uncouple when so rotated. However, couplers have been known to uncouple during this rotation.
To prevent such an inadvertent release of the couplers, various devices have been incorporated as part of the coupler and particularly as part of a lock within a head of the coupler. The function of such a device is to limit movement of the lock when the coupler has been inverted to an extent that a knuckle of the coupler remains locked. When the coupler is in an upright position, the device allows normal coupler operation.
One such device is disclosed in U.S. Pat. No. 1,612,775 for use with the now obsolete Type D coupler.
Another anti-unlocking device for use with the now standard (AAR) Type F coupler is disclosed in U.S. Pat. No. 3,433,369.